Epicardial defibrilation lead with side helix fixation and placement thereof

ABSTRACT

A method and system for employing a medical device is disclosed. The medical device includes a housing, a processor disposed within the housing, a connector module, and a medical electrical epicardial lead connected to the processor through the connector module. The epicardial lead is used to sense a cardiac signal from tissue of a patient. The lead comprises an insulative lead body that includes a proximal end and a distal end, at least one conductor disposed in the lead body, and a side helical fixation member, disposed a distance from the distal end, the side helical fixation member. The side helical fixation member comprises a set of windings configured to wrap around the lead body circumference. The side helical fixation member includes a distal tip comprising a sharpened elongated flat free end that is perpendicular to the lead body and angled toward an inside of the set of windings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/204,343, filed on Aug. 12, 2015 and U.S. Provisional Application No.62/211,331 filed on Aug. 28, 2016. The disclosures of the aboveapplications are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to implantable medical leads,and, more particularly, to techniques for placement of medicalelectrical leads.

BACKGROUND

The human anatomy includes many types of tissues that can eithervoluntarily or involuntarily, perform certain functions. After disease,injury, or natural defects, certain tissues may no longer operate withingeneral anatomical norms. For example, after disease, injury, time, orcombinations thereof, the heart muscle may begin to experience certainfailures or deficiencies. Certain failures or deficiencies can becorrected or treated with implantable medical devices (IMDs), such asimplantable pacemakers, implantable cardioverter defibrillator (ICD)devices, cardiac resynchronization therapy defibrillator devices, orcombinations thereof.

IMDs detect and deliver therapy for a variety of medical conditions inpatients. IMDs include implantable pulse generators (IPGs) orimplantable cardioverter-defibrillators (ICDs) that deliver electricalstimuli to tissue of a patient. ICDs typically comprise, inter alia, acontrol module, a capacitor, and a battery that are housed in ahermetically sealed container with a lead extending therefrom. It isgenerally known that the hermetically sealed container can be implantedin a selected portion of the anatomical structure, such as in a chest orabdominal wall, and the lead tip portion can be positioned at theselected position near or in the muscle group. When therapy is requiredby a patient, the control module signals the battery to charge thecapacitor, which in turn discharges electrical stimuli to tissue of apatient via electrodes disposed on the lead, e.g., typically near thedistal end of the lead. Typically, a medical electrical lead includes aflexible elongated body with one or more insulated elongated conductors.Each conductor electrically couples a sensing and/or a stimulationelectrode of the lead to the control module through a connector module.

In order to deliver stimulation or to perform sensing functions, it isdesirable for the distal end of a medical electrical lead tosubstantially remain in its position, as originally implanted by aphysician. Leads are typically implanted endocardially such that thelead is transvenously introduced with the distal end of the leadpositioned in one of the chambers. In contrast to endocardial leads,epicardial leads are introduced outside of the cardiovascular system tobring the distal end in contact with the epicardial or myocardialtissue. Numerous scenarios exist in which epicardial leads are preferredover endocardial leads such as when patients possess inadequate vascularaccess. Children, for example, may require an epicaridal lead instead ofan endocardial lead. Additionally, some congenital heart diseasepatients require the use of an epicardial lead. Moreover, patients inwhich placement of a lead through the coronary sinus for delivery ofcardiac resynchronization therapy that has failed may benefit byplacement of an epicardial lead in a more optimal pacing site locationsuch as the outer surface of the heart.

Epicardial lead implantation requires surgical access to allowsufficient room to position and fixate the pacing lead by either suturesor a right angle helical screw component. Surgical access is moretraumatic and requires longer recovery time as compared to percutaneousimplant methods. One such percutaneous implant method has been describedin Subxiphoid Approach to Epicardial Implantation of ImplantableCardioverter Defibrillators in Children, Sertac Haydin, M. D. et al.PACE, Vol. 00 (2013). In the Haydin article, a transvenous ICD lead wasintroduced through a subxiphoid percutaneous approach such that theextendable-retractable helix was screwed into non-cardiac tissue forfixation without pacing or sensing capability through the ICD lead.

Another epicardial implantation method is described in U.S. Pat. No.5,443,492 to Stokes et al. which involves an epicardial lead in which anactive fixation mechanism secures the lead in place while allowing adistal electrode on the lead to mechanically “float” with respect to thebody tissue. The active fixation mechanism comprises a curved hookdisposed at the distal end of the lead. The curved hook defines a helixaround at least a portion of the lead's circumference. A hollowintroducer needle is slidably disposed on the lead. The hollow needleprovided with a longitudinal slit in a distal section of is length, suchthat the distal section of the needle can be advanced over the distalend of the lead, past the fixation hook, which is received in thelongitudinal slit.

The Stokes et al. lead is unable to be fixated solely in the epicardialtissue since the lead penetrates beyond the epicardium, and residesmid-myocardial for stimulation. This is due to the hollow needle thatinterlocks with the side hook. The needle is jabbed into the surfacedriving the tip (i.e. electrode) of the lead deeply into the heartmyocardium. The needle is then twisted or torqued (i.e. bayonet style)into the tissue. Thereafter, the needle is withdrawn leaving the leadtip disposed intramyocardial.

Numerous other lead configurations have employed side helical fixationmembers such as U.S. Pat. No. 8,755,909 B2 to Sommer et al. incorporatedby reference in its entirety. One type of left lead adapted forplacement in the coronary vasculature is that disclosed in U.S. Pat. No.7,860,580, issued to Sommer, et al. and incorporated herein by referencein its entirety. Another type of left lead adapted for placement in thecoronary vasculature is that disclosed in U.S. Pat. No. 7,532,939,issued to Sommer, et al. and also incorporated herein by reference inits entirety. The side helixes from Sommer cannot be used to solelyattach to epicardial tissue since the free end of the Sommer side helixis configured to engage thinner tissue for coronary vein fixation.

Additional designs for a side-helix leads are disclosed in U.S. Pat. No.5,443,492, issued to Stokes, et al. U.S. Pat. No. 7,529,584, issued toLaske, et al, U.S. Pat. No. 7,313,445, issued to McVenes, et al., U.S.Pat. No. 6,493,591, issued to Stokes, U.S. Pat. No. 6,556,874, issued toAudoglio, all of which are incorporated herein in their entireties.

It is desirable to develop a medical electrical lead that minimizestrauma to the tissue and solely attaches to the epicardial tissue.

SUMMARY

The present disclosure comprises an implantable medical device thatincludes a housing, a processor disposed within the housing, and amedical electrical epicardial lead connected to the processor through aconnector module. The epicardial lead is used to sense cardiac signalsfrom tissue of a patient. The lead comprises an insulative lead bodythat includes a proximal end and a distal end, at least one conductordisposed in the lead body, and a side helical fixation member, disposeda distance from the distal end, the side helical fixation member. Theside helical fixation member comprises a set of windings configured towrap around the lead body circumference. The side helical fixationmember includes a distal tip comprising a sharpened elongated flat freeend that is perpendicular to the lead body and angled toward an insideof the set of windings. In response to the sensed cardiac signal, thedevice delivers electrical pulses through the epicardial lead.

The epicardial lead of the present disclosure resides solelyepicardially and allows fixation more proximal on the lead body comparedto the epicardial lead of Stokes et al. The lead stays only on theepicardial surface since the side helical member attaches or grabs theouter surface of the epicardium and cannot pass into the myocardium dueto the tissue being wedged therein. The lead body and electrodes remainbetween the pericardial sac layer and the epicardium. The epicardiallead of the present disclosure allows a distal defibrillation electrodeand a left ventricle pace/sense electrode to be placed along a pathextending from the subxiphoid access location.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, wherein likenumerals denote like elements.

FIG. 1A is a conceptual schematic view of a patient with an implantablemedical device in which a medical electrical lead extends therefrom.

FIG. 1B is a conceptual schematic view of a patient with an implantablemedical device in which a medical electrical lead extends therefrom.

FIG. 2 is a functional block diagram of the IMD shown in FIG. 1.

FIG. 3 is a schematic view of a heart and a cross-section of hearttissue.

FIG. 4 is a conceptual schematic view of an implantable medical devicein which a medical electrical lead extends therefrom as depicted in FIG.1A.

FIG. 5 is a conceptual schematic view of an implantable medical devicein which a medical electrical lead extends therefrom as depicted in FIG.1B.

FIG. 6 is a schematic view of an elongated bipolar epicardial lead.

FIG. 7 is a schematic view of an elongated epicardial lead.

FIG. 8A depicts a lead body without a side helix fixation member.

FIG. 8B depicts a lead body with a side helix fixation member.

FIG. 9A depicts a schematic isometric view of the side helix fixationmember having a portion or window open from a top view.

FIG. 9B depicts a schematic isometric view of the side helix fixationmember having a portion or window cut-away from a side view.

FIG. 9C depicts a cross-sectional view along a longitudinal axis of theside helix fixation member with a portion cut-away.

FIG. 9D is an orthographic view of the side helix fixation memberdepicted in FIG. 9C.

FIG. 10A depicts a schematic isometric view of a conventional sidehelical fixation member according to the prior art in which a distanceD1 exists between the first and second winds.

FIG. 10B depicts a cross-sectional view along a longitudinal axis of theconventional side helical fixation member shown in FIG. 10A, accordingto the prior art.

FIG. 10C is an orthographic view of the side helical fixation memberdepicted in FIG. 10B, according to the prior art.

FIG. 11A depicts a schematic isometric view of the side helical fixationmember and is compared to the conventional side helical fixation memberof FIG. 10A.

FIG. 11B depicts a cross-sectional view along a longitudinal axis of theside helical fixation member and is compared to the conventional sidehelical fixation member of FIG. 10A.

FIG. 11C is an orthographic view of the side helical fixation memberdepicted in FIG. 10B.

FIG. 12 is a plan view of an exemplary medical electrical lead connectedthrough to a guide catheter

FIG. 13 is a flow diagram of a method of implanting an epicardialmedical electrical lead.

FIG. 14 is a flow diagram of a method of using an epicardial medicalelectrical lead.

FIG. 15 is a schematic diagram depicting a catheter.

FIG. 16A is a schematic diagram depicting a side view of an embodimentof a catheter tip.

FIG. 16B is a schematic diagram depicting a view of the catheter tip ofFIG. 16A in which a concave surface of the catheter tip surface is shownwith a substantially open rectangular portion.

FIG. 16C is a schematic diagram depicting a side view of the cathetertip of FIG. 16A slightly rotated to show a side of the tip.

FIG. 16D is a schematic diagram depicting a side view of the cathetertip of FIG. 16C slightly rotated relative to FIG. 16C to show a side ofthe tip.

FIG. 17A is a schematic diagram depicting a side view of an embodimentof a catheter tip.

FIG. 17B is a schematic diagram depicting a view of the catheter tip ofFIG. 17A in which a concave surface of the catheter tip surface is shownwith a substantially open rectangular portion formed by sides andproximal and distal ends of the tip.

FIG. 17C is a schematic diagram depicting a side view of an embodimentof a catheter tip.

FIG. 17D is a schematic diagram depicting a view of the catheter tip ofFIG. 17C in which a concave surface of the catheter tip surface is shownwith a substantially open elliptical portion formed by sides andproximal and distal ends of the tip.

FIG. 17E is a schematic diagram depicting a side view of an embodimentof a catheter tip.

FIG. 17F is a schematic diagram depicting a view of the catheter tip ofFIG. 17E in which a concave surface of the catheter tip surface is shownwith a substantially open elliptical portion formed by sides andproximal and distal ends of the tip.

FIG. 18A is a schematic diagram depicting a side view of an embodimentof a catheter tip having an angled cut along sides of the tip.

FIG. 18B is a schematic diagram depicting a view of the catheter tip ofFIG. 18A in which a concave surface of the catheter tip surface is shownwith a substantially open elliptical portion formed by sides andproximal and distal ends of the tip.

FIG. 18C is a schematic diagram depicting a side view of an embodimentof a catheter tip having sides cut away in a manner to form asubstantially rectangular open portion.

FIG. 18D is a schematic diagram depicting a view of the catheter tip ofFIG. 18C in which a concave surface of the catheter tip surface is shownwith a substantially open rectangular portion formed by sides andproximal and distal ends of the tip.

DETAILED DESCRIPTION

One or more embodiments relate to an implantable medical device thatincludes a medical electrical epicardial lead. The lead includes (a) aninsulative lead body that includes a proximal end and a distal end, (b)at least one conductor disposed in the lead body, and (c) a side helicalfixation member, disposed a distance from the distal end. The sidehelical fixation member comprises a set of windings configured to wraparound the lead body circumference. The side helical fixation memberfurther includes a distal tip comprising a sharpened elongated flat freeend that is perpendicular to the lead body and angled toward inside ofthe set of windings. The sharpened elongated flat free end is configuredto attach solely to epicardial tissue. In particular, the epicardiallead of the present disclosure is configured for deeper tissueengagement than other leads (e.g. U.S. Pat. No. 8,755,909 B2 to Sommeret al.) that are configured for attachment to thinner tissue such as theinside of coronary veins.

Skilled artisans will appreciate that the epicardial lead, disclosedherein, can be used for delivery of therapies such ascardioresynchronization therapy (CRT), defibrillation, and/or anybradycardia indication. In particular, the epicardial lead utilizes alumenless lead body design, distal high voltage coil to be positioned inthe superior region of the pericardial space (i.e. transverse sinus) andfixated with a side fixation helix just proximal to the high voltagecoil into the epicardial surface of the posterior left ventricle (LV).Either one or two ring electrodes are positioned just proximal to theside fixation helix to provide ventricular pacing and sensing withadditional atrial sensing in the integrated bipolar vector.

Placement of the epicardial lead can be performed using a telescopingcatheter without performing a thoracotomy, which can be painful andpotentially cause a patient to develop a pneumonia. Moreover, no pleuralbreach is required to perform delivery of the lead described herein.Consequently, only a single day of treatment in a hospital setting maybe needed which is similar to placement of an endocardial lead for CRT(e.g. left ventricular only pacing, biventricular pacing etc.). Generalanesthesia is typically unnecessary for this method thereby furtherreducing complications associated with surgery. Epicardial leads can bebeneficial to patients in which vascular access is less of an option.Moreover, epicardial leads have unrestricted access to optimal sites onthe left ventricle or other cardiac tissue sites for delivery ofelectrical stimulation which may enhance therapies such as CRT,defibrillation, or delivery of pacing pulses.

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Thedevices described herein include an exemplary number of leads, etc. Onewill understand that the components, including number and kind, may bevaried without altering the scope of the disclosure. Also, devicesaccording to various embodiments may be used in any appropriatediagnostic or treatment procedure, including a cardiac procedure. Theepicardial leads disclosed herein are typically chronically implanted ina patient.

FIGS. 1A-1B depict a medical device system 10 coupled to a heart 8 of apatient 2 by way of an epicardial lead 18, which is stabilized throughan anchoring sleeve, depicted in FIG. 7, used in a conventional fashionto stabilize the lead at the insertion site. Referring briefly to FIG.3, heart 8 comprises endocardium, myocardium, epicardium (i.e. viscerallayer of serous pericardium), pericardial cavity, parietal layer ofserous pericardium and fibrous pericardium. Each layer exhibits adifferent level of resistance to force that may be used to pierce one ormore layers in order to affix an implantable medical device to tissue.

FIG. 1A depicts an epicardial lead 18 placed on heart 8 as shownrelative to FIG. 4 for delivery of CRT. For example, lead 18 includes aset of electrodes comprising pace and or sense electrodes 34, 36 and adefibrillation electrode 38. defibrillation electrode 38 can optionallyinclude an atrial sensing vector. Defibrillation electrode 38 is placedover the pulmonary artery to the right atrium. The lead 18 furtherincludes a left ventricular pace/sense electrode 34 placed on the leftventricle, a right ventricular pace sense electrode 36. A side helicalfixation member 30, coupled to the epicardial lead 18, is attached tothe epicardium.

FIG. 1B depicts an epicardial lead 18 placed on heart 8 as shownrelative to FIG. 5 for delivery of CRT. In particular, FIG. 1B depicts aleft ventricular pace/sense electrode 34 near left ventricle, a rightventricular pace sense electrode 36 with a side helical fixation membertherebetween along an epicardial lead 18.

A medical device system 10 includes a medical device housing 12 having aconnector module 14 (e.g. international standard (IS)-4, defibrillation(DF)-1, DF-4 etc.) that electrically couples various internal electricalcomponents housed in medical device housing 12 to a proximal end of amedical electrical lead 18. A medical device system 10 may comprise anyof a wide variety of medical devices that include one or more medicallead(s) 18 (e.g. bipolar side helix lead) and circuitry coupled thereto.An exemplary medical device system 10 can take the form of animplantable cardiac pacemaker, an implantable cardioverter, animplantable defibrillator, an implantable cardiacpacemaker-cardioverter-defibrillator (PCD), a neurostimulator, a tissueand/or muscle stimulator. IMDs are implanted in a patient in anappropriate location. Exemplary IMDs are commercially available asincluding one generally known to those skilled in the art, such as theMedtronic CONCERTO™, SENSIA™, VIRTUOSO™, RESTORE™, RESTORE ULTRA™, VIVA™sold by Medtronic, Inc. of Minnesota. Aspects of the disclosure can beused with many types and brands of IMDs. Medical device system 10 maydeliver, for example, pacing, cardioversion or defibrillation pulses toa patient via electrodes disposed on distal end of one or more lead(s).Specifically, the lead may position one or more electrodes with respectto various cardiac locations so that medical device system 10 candeliver electrical stimuli to the appropriate locations.

Lead 18 includes an elongated lead body 17 (shown in greater detail inFIG. 6 and FIGS. 8A-8B). Lead 18 utilizes a lumenless lead body design,distal high voltage coil to be positioned in the superior region of thepericardial space (i.e. transverse sinus) and fixated with a sidefixation helix just proximal to the high voltage coil into theepicardial surface of the posterior LV. Lead body 18 extends from aproximal end 15 to a distal end 19 at the tip 37 of the lead 18. In oneor more embodiments, lead body 17 can be size 4 or less French. One ormore other embodiments involve lead body 17 sizes up to 9/10 Frenchsince an increased diameter can increase electrode surface area fordefibrillation. Lead body 17 can include one or more jacketed elongatedconductive elements 40 a,b. A jacket 35 (also referred to as a layer,longitudinal element, coating, tubing etc.) extends longitudinally andaround the conductive elements 40 a,b to insulate one or more conductiveelements 40 a,b.

Electrically conductive elements 40 a,b for lead 18 can include coils,wires, coil wound around a filament, cables, conductors or othersuitable members. Conductive elements 40 can comprise platinum, platinumalloys, titanium, titanium alloys, tantalum, tantalum alloys, cobaltalloys (e.g. MP35N, a nickel-cobalt alloy etc.), copper alloys, silveralloys, gold, silver, stainless steel, magnesium-nickel alloys,palladium, palladium alloys or other suitable materials. Electricallyconductive element 40 a, is covered, or substantially covered,longitudinally with a jacket (also referred to as a layer, alongitudinal element, a longitudinal member, a coating, a tubularelement, a tube or a cylindrical element). Typically, the outer surfaceof electrodes such as the ring electrode, the tip electrode, and thedefibrillation coil 27 are exposed or not covered by a jacket or layerso that electrodes can sense and/or deliver electrical stimuli to tissueof a patient.

Fixation mechanism 30 (e.g. side helix) or side helical member can belocated at the distal end of lead 18 to attach the lead 18 to epicardialtissue. Referring to FIGS. 9A-9F, various views of the side helicalfixation member 30 are shown. The side helical member 30 is configuredsuch that it extends radially outward from the lead for a short distanceand then coils helically around at least a portion along thelongitudinal axis of the lead body circumference. The location of thehelical fixation member 30 is based on the specific application andintended cardiac anatomy. For small anatomies, such as pediatricpatients, the helix location may range from about 3 cm to about 6 cmfrom the distal tip to allow positioning of a defibrillation electrodeof about 2 cm to about 5 cm long. For large anatomies such as adultheart failure and dilated cardiomyopathies the helix location may rangefrom 6 cm to 12 cm from the distal tip to allow positioning of adefibrillation electrode of 4 cm to 8 cm long and leftventricular/atrial pace sense electrode. The side helical member 30, forexample, includes a helical pitch with an inner diameter of about 1French or less up to equal to that of the lead body diameter (e.g. 3.2French to 4.1 French for a 4.1 French lead body), an main outer diameter(OD) of about equal to the lead body outer diameter to 1.5 French larger(4.1 French to 5.5 French for a 4.1 French lead body), and a length ofabout 3.4 mm to about 4 mm in order to screw into tissue. Side helicalfixation member 30 employs a right wound coil or spring configuration. Aright wound coil or spring configuration involves right hand woundspring spirals which turns in the same direction as a right handthreaded screw. For example, a front point, on the spiral, travels up tothe right, as shown in FIGS. 9B-9C. The side helical fixation member 30includes a window portion 32 (also referred to as an open or cut-awayportion) formed by length side W_(L) and window width W_(W). The windowportion serves two functions. First, mechanical interlocking is achievedwith the open window 32. For example, polyurethane is placed on theoutside surface of a fused helical tubular section. The polyurethane iseither melted and/or reflowed through the window portion 32 over thewindings. Consequently, the side helical member 30 is locked or affixedto the lead body 17.

Second, window 32 allows the physician to visualize the turns of theside helix using the fluoroscopy during the implantation procedure. Forexample, the physician can position the lead, and, when ready, watch asthe helix turns using the window portion 32 as a means to track turningof the side helical fixation member 30. Without fluoroscopy, either avideoscope is used to visualize turning of the side helix or lead bodytorque feedback is employed as described in U.S. patent application Ser.No. 14/696,242, entitled METHOD AND APPARATUS FOR DETERMININGSUITABILITY OF A LEAD IMPLANT LOCATION, incorporated by reference in itsentirety herein.

In one or more embodiments of the side helical fixation member 30,depicted in FIG. 9A and FIG. 11A, includes a longitudinal length L thatextends about 0.142 inches from the very distal end to the proximal end.Radial distances, denoted as A, B, in FIG. 11B for side helix are basedon the outer diameter (OD) plus 30%, 60% and 90% of the wire diameter,respectively. Exemplary dimensions for A and B are 0.0620 inches and0.046 inches, respectively.

A side-to-side comparison is made between a conventional side helicalfixation member 50, shown in FIGS. 10A-10C (prior art) and a sidehelical member 30 of the present disclosure shown in FIGS. 11A-11C.Referring to FIGS. 10A-10C, conventional side helix 50, shown anddescribed in U.S. Pat. No. 7,860,580, issued to Sommer, was designed forcoronary vein fixation. In particular, side helical member 50 isconfigured to engage thinner tissue along a concave surface such as theinner cylindrical surface of the coronary vein wall.

Side helical members 30, 50 extend a length L and comprise a set ofwindings configured to wrap around the circumference of lead body 17. Asharpened tip is located at a distal end of the side helical member 50.Side helical member 50 has a first wind 60 that extends an axialdistance D1 to the second wind 62. The side helical member 30 shown inFIG. 11A has a first wind 64 that extends a distance D2 to the secondwind 66. D1 is substantially less than distance D2. For example,referring to FIG. 10B, the first and second winds 60, 62 have radialdimensions of about 0.0337 inches and 0.0350 inches, respectivelymeasured away from the center 39 of the helix barrel. In comparison, thefirst and second winds 64, 66 are about 0.036 inches and 0.040 inches,respectively.

Other differences exist between side helical members 30, and 50. Forexample, referring to FIG. 10B, side helical member 50 has an angletheta (e) into the first wind, defined by surfaces S1 and S2. Angle θ isconsidered shallow (e.g. about 18°). In contrast, side helical member 30shown in FIG. 11B has a steep angle omega (Ω) into the first wind. AngleΩ is defined by surfaces S1 and S2, which is about 30°. In one or moreother embodiments, Ω can be 25° or more.

In addition, side helical member 50 shown in FIG. 10B has a steep anglephi (ϕ) (e.g. 25°, 30°, 35° etc.) into the tip defined by surfaces S3and S2 while side helical member 30 comprises angle alpha (α) defined bysurfaces S2 and S3. Alpha α is less than phi ϕ. For example, alpha α canbe less than 25°, equal to or less than 20°, equal to or less than 18°.Yet another difference exists by the angle {acute over (ω)} (FIG. 10B)and angle § (FIG. 11B) formed between surface S3 and line S4. Line S4 isperpendicular to the center 39 of the barrel. Angle {acute over (ω)} is20° or more while angle § is 15° or less.

Additionally, side helical member 50 shown in FIG. 10B possesses ahelical tip of about 0.039 inches measured from a longitudinal axis 39or centerline of the helical member 50 to the tip whereas side helicalmember 30 possesses a substantially greater helical tip of about 0.056inches measured from a longitudinal axis. Moreover, the maximum diameterfrom the longitudinal axis of the helical member is 0.074 inches forhelical member 50 as compared to 0.096 inches for side helical member.

Referring to FIGS. 10B-10C, the angle of the free end 33 or kick-out ofhelical member 50 is shown as being a small angle (e.g. less than 90°).In contrast, the angle of the free end or kick-out shown in FIG. 11C isgreater than 350° for the helical fixation member 30. Additionally, onthe last wind of side helical member 30, a very flat pitch (denoted as §in FIG. 11B) is used on the tip to increase stability and reduceauto-rotation (i.e. turning of the helix with tensile force). Incomparison, side helical member 50 uses a 45° angle and has a highdegree of autorotation. In one or more embodiments, the side helicalmember 30 is not electrically active. In another embodiment, sidehelical member 30 can be configured to be electrically active. Exemplarywire gauge used is 26-36 AWG bare wire or that optionally includestitanium nitride coating having a one to one ratio. Side helicalfixation member 30 is configured to have a minimum of a ¾ turn toachieve excellent fixation on a tangent to the heart surface. Helicalfixation member 30 enters and passes through and out of the epicardium.

In addition to side helical member 30, lead 18 includes electrodes.Optionally, one or more of the electrodes, such as on the epicardiallead, can be drug eluting such as that which is disclosed in US20140005762 filed Jun. 29, 2012, assigned to the assignee of the presentinvention, is incorporated by reference in its entirety. Additionally,the tip and ring electrodes can be coated with titanium nitride (TiN).Optionally, a flexible anode ring electrode can be included on the lead.The flexible anode ring electrode can comprise bare platinum/iridium(Pt/Ir). The electrodes can take the form of ring and barrel shapedelectrodes, respectively, as described in U.S. Pat. No. 8,825,180 byBauer, et al., incorporated herein by reference in its entirety. Theelectrodes can include steroid (e.g. beclomethasone) eluting MCRD's.Other known electrode designs may of course be substituted.

Exemplary lead insulation that can be used in conjunction with thepresent disclosure are shown and described with respect to U.S. Pat. No.8,005,549 issued Aug. 23, 2011, U.S. Pat. No. 7,783,365 issued Aug. 24,2010, and assigned to the assignee of the present invention, thedisclosure of which are incorporated by reference in their entiretyherein. ATTAIN PERFORMA™ Model 4298 quadripolar lead insulation isanother exemplary insulative material that can be used.

Examples of connector modules may be seen with respect to U.S. Pat. No.7,601,033 issued Oct. 13, 2009, U.S. Pat. No. 7,654,843 issued Feb. 2,2010, and assigned to the assignee of the present invention, thedisclosure of which are incorporated by reference in their entiretyherein. Connector module 14, as illustrated, takes the form of a DFquadripolar connector, but any appropriate connector mechanism (e.g.IS1/DF1 as bipolar/unipolar connectors etc.) may be substituted.Connector module 14 electrically couples a proximal end of each lead tovarious internal electrical components of implantable medical device 10through a connector or set screw.

FIG. 2 is a functional block diagram of IMD 10. IMD 10 generallyincludes timing and control circuitry 52 and an operating system thatmay employ processor 54 for controlling sensing and therapy deliveryfunctions in accordance with a programmed operating mode. Processor 54and associated memory 56 are coupled to the various components of IMD 10via a data/address bus 55. Processor 54, memory 56, timing and control52, and capture analysis module 80 may operate cooperatively as acontroller for executing and controlling various functions of IMD 10.

Processor 54 may include any one or more of a microprocessor, acontroller, a digital state machine, a digital signal processor (DSP),an application specific integrated circuit (ASIC), a field-programmablegate array (FPGA), or equivalent discrete or integrated logic circuitry.In some examples, processor 54 may include multiple components, such asany combination of one or more microprocessors, one or more controllers,one or more DSPs, one or more ASICs, or one or more FPGAs, as well asother discrete or integrated logic circuitry. The functions attributedto processor 54 herein may be embodied as software, firmware, hardwareor any combination thereof. In one example, capture analysis module 80and/or sensing module 60 may, at least in part, be stored or encoded asinstructions in memory 56 that are executed by processor 54.

IMD 10 includes therapy delivery module 51 for delivering a therapy inresponse to determining a need for therapy based on sensed physiologicalsignals. Therapy delivery module 50 includes a signal generator forproviding electrical stimulation therapies, such as cardiac pacing orarrhythmia therapies, including CRT. Therapies are delivered by module50 under the control of timing and control 52. Therapy delivery module50 is coupled to two or more electrodes 68 via a switch matrix 58 fordelivering pacing pulses to the heart. Switch matrix 58 may be used forselecting which electrodes and corresponding polarities are used fordelivering electrical stimulation pulses. Electrodes 68 may correspondto the electrodes 12, 30, 34, 36 and 38 shown in FIG. 1 or anyelectrodes coupled to IMD 10.

Timing and control 52, in cooperation with processor 54 and captureanalysis module 80, control the delivery of pacing pulses by therapydelivery 50 according to a programmed therapy protocol, which includesthe option of multi-site pacing wherein multiple pacing sites along aheart chamber are selected using methods described herein. Selection ofmultiple pacing sites and control of the pacing therapy delivered may bebased on results of activation time measurements or an anodal captureanalysis algorithm or a combination of both. As such, capture analysismodule 80 is configured to determine pacing capture thresholds anddetect the presence of anodal capture for determining both anodal andcathodal capture thresholds for a given pacing vector in someembodiments.

Electrodes 68 are also used for receiving cardiac electrical signals.Cardiac electrical signals may be monitored for use in diagnosing ormonitoring a patient condition or may be used for determining when atherapy is needed and in controlling the timing and delivery of thetherapy. When used for sensing, electrodes 68 are coupled to sensingmodule 60 via switch matrix 58. Sensing module 60 includes senseamplifiers and may include other signal conditioning circuitry and ananalog-to-digital converter. Cardiac EGM signals (either analog sensedevent signals or digitized signals or both) may then be used byprocessor 54 for detecting physiological events, such as detecting anddiscriminating cardiac arrhythmias, determining activation patterns ofthe patient's heart, measuring myocardial conduction time intervals, andin performing anodal capture analysis and pacing capture thresholdmeasurements as will be further described herein.

IMD 10 may additionally be coupled to one or more physiological sensors70. Physiological sensors 70 may include pressure sensors,accelerometers, flow sensors, blood chemistry sensors, activity sensorsor other physiological sensors for use with implantable devices.Physiological sensors may be carried by leads extending from IMD 10 orincorporated in or on the IMD housing. Sensor interface 62 receivessignals from sensors 70 and provides sensor signals to sensing module60. In other embodiments, wireless sensors may be implanted remotelyfrom IMD 10 and communicate wirelessly with IMD 10. IMD telemetrycircuitry 64 may receive sensed signals transmitted from wirelesssensors. Sensor signals are used by processor 54 for detectingphysiological events or conditions.

The operating system includes associated memory 56 for storing a varietyof programmed-in operating mode and parameter values that are used byprocessor 54. The memory 56 may also be used for storing data compiledfrom sensed signals and/or relating to device operating history fortelemetry out upon receipt of a retrieval or interrogation instruction.The processor 54 in cooperation with therapy delivery module 50, sensingmodule 60 and memory 56 executes an algorithm for measuring activationtimes for selecting pacing sites for delivering multi-site pacing.

A capture analysis algorithm may be stored in memory 56 and executed byprocessor 54 and/or capture analysis module 80 with input received fromelectrodes 68 for detecting anodal capture and for measuring pacingcapture thresholds. Microprocessor 54 may respond to capture analysisdata by altering electrode selection for delivering a cardiac pacingtherapy. Data relating to capture analysis may be stored in memory 56for retrieval and review by a clinician and that information may be usedin programming a pacing therapy in IMD 10.

IMD 10 further includes telemetry circuitry 64 and antenna 65.Programming commands or data are transmitted during uplink or downlinktelemetry between IMD telemetry circuitry 64 and external telemetrycircuitry included in programmer 90.

Programmer 90 may be a handheld device or a microprocessor based homemonitor or bedside programming device used by a clinician, nurse,technician or other user. IMD 10 and programmer 90 communicate viawireless communication. Examples of communication techniques may includelow frequency or radiofrequency (RF) telemetry using Bluetooth or MICSbut other techniques may also be used.

A user, such as a physician, technician, or other clinician, mayinteract with programmer 90 to communicate with IMD 10. For example, theuser may interact with programmer 90 to retrieve physiological ordiagnostic information from IMD 10. Programmer 90 may receive data fromIMD 10 for use in electrode selection for CRT, particularly dataregarding cathodal and anodal capture thresholds and other measurementsused in electrode selection such as hemodynamic measurements and LVactivation times. A user may also interact with programmer 90 to programIMD 10, e.g., select values for operational parameters of the IMD. Forexample, a user interacting with programmer 90 may select programmableparameters controlling a cardiac rhythm management therapy delivered tothe patient's heart 8 via any of electrodes 68.

Processor 54, or a processor included in programmer 90, is configured tocompute battery expenditure estimates in some embodiments. Usingmeasured pacing capture thresholds and lead impedance measurements,along with other measured or estimated parameters, the predicted batterylongevity of the IMD 10 may be computed for different pacingconfigurations. This information may be used in selecting orrecommending a multi-site pacing configuration. As such, IMD 10 isconfigured to perform lead impedance measurements and determine otherparameters required for estimated energy expenditure calculations, whichmay include but are not limited to a history of pacing frequency,capture thresholds, lead impedances, and remaining battery life.

While not shown explicitly in FIG. 2, it is contemplated that a user mayinteract with programmer 90 remotely via a communications network bysending and receiving interrogation and programming commands via thecommunications network. Programmer 90 may be coupled to a communicationsnetwork to enable a clinician using a computer to access data receivedby programmer 90 from IMD 10 and to transfer programming instructions toIMD 10 via programmer 90. Reference is made to commonly-assigned U.S.Pat. No. 6,599,250 (Webb et al.), U.S. Pat. No. 6,442,433 (Linberg etal.) U.S. Pat. No. 6,622,045 (Snell et al.), U.S. Pat. No. 6,418,346(Nelson et al.), and U.S. Pat. No. 6,480,745 (Nelson et al.) for generaldescriptions and examples of network communication systems for use withimplantable medical devices for remote patient monitoring and deviceprogramming, hereby incorporated herein by reference in their entirety.

FIG. 10 is a plan view of an exemplary medical electrical lead connectedthrough to a delivery device or guide catheter such as the ATTAINCATHETER® developed and sold by Medtronic, Inc. of Minneapolis, Minn.The lead is configured to deliver electrical stimulation to tissueand/or sense signals from the tissue. The lead includes proximal end anda distal end with a lead body therebetween that generally defines alongitudinal axis. At the proximal end is located an in-line bipolarconnector assembly 14. The distal end, which includes set of electrodes(e.g., can be configured in many different ways to ensure the lead staysin position to deliver electrical therapy to cardiac tissue.

FIG. 13 depicts a minimally invasive pericardial access method 200 fordelivering an epicardial lead 18 to any location on the surface of theheart. The guiding catheter 100, described herein, is configured toplace the epicardial lead 18 on the outer surface of the ventricle (leftventricle (LV), right ventricle (RV)) or the atrium (left atrium (LA),right atrium (RA)) without use of negative pressure or suction to placethe lead. In one or more embodiments, catheter 100 is designed as afixed shape to wrap around the surface of the heart in order to reachatria or ventricle (LV, RV). Guide catheter 100 can be configured toinclude a single catheter or telescoping catheter system comprisinginner and outer catheters (e.g. ATTAIN COMMAND™ (e.g. outer catheter)and ATTAIN SELECT II™ (e.g. inner catheter). Exemplary delivery devicescan also be used such as the ATTAIN PERFORMA™ Model 4298 commerciallyavailable from Medtronic. Another exemplary delivery device may be seenwith respect to U.S. Pat. No. 9,155,868 issued May 5, 2015, and assignedto the assignee of the present invention, the disclosure of which isincorporated by reference in its entirety herein. Another exemplarydelivery system is configured to stabilize the lead and provide spacefor the lead delivery catheter for lead 18 placement on the epicardialsurface. The delivery system can comprise of a telescoping cathetersystem. The outer catheter has a balloon on the distal tip to bothstabilize the catheter and also provide support and space for the innercatheter. The inner catheter telescopes through and extends beyond thedistal tip of the outer balloon catheter and has a 90 degree or morecurve on the distal end that directs the lead into the correct positionfor engagement into the epicardial surface.

The method of placing the lead 18 begins at block 202 in which the lead18 is loaded into a valve of the guide catheter 100, as shown in FIG.12. At block 204, pericardial access is attained through a supxiphoidalpuncture with a small needle such as a Tuohy needle ranging in size fromabout 22 G to about 25 G. In particular, to ensure the process isminimally invasive, a percutaneous puncture is employed with a leftlateral (i.e. intercostal) thoracascope port for visualization. At block206, a guiding catheter 100 or delivery device is introduced into thepericardial space. The outer catheter 104 is deflected by rotating thehandle 102. The guiding catheter 100 includes an outer deflectablecatheter 104 and an inner catheter assembly 108 that are positionablewithin a lumen of the outer catheter and extendible beyond a distal endof the outer catheter. The inner catheter assembly 108 includes apre-formed inner catheter 104 (e.g. shaft configurations can be, forexample, cf3 and cf4) with a soft tip. In one or more other embodiments,catheter 108 is configured to be employed as a single catheter as shownin FIG. 15 with a lumen (not shown) to receive epicardial lead 18.Catheter 108 comprises a set of segments 110-118 in which the distal tip118 comprises softer and more flexible material (i.e. 35 durometer (D))compared to more proximal segments 110-116. For example, one inchsegments 112, 114 and 116 comprise 72 D, 63 D, and 55 D, respectively.Softer more flexible material is used at distal tip 118 as compared tosegments 112-116. Distal tip 116 extends about one inch from segment116. Distal tip 118 allows for easier navigation of the catheter in thepatient's body. The distal tip 118 of catheter 108 can include a varietyof different shapes, as is shown in FIGS. 16-18 and described in theaccompanying text.

At block 208, the guiding catheter 100 (e.g. outer catheter if inner andouter catheter are used) is navigated to the optimal location such thatlead 18 approaches the pericardial space of the heart after passingthrough the subxiphoid access. The epicardial fixation lead 18 includesa side fixation helix oriented to solely grasp the epicardial tissue butthe side fixation helix 30. Epicardial lead 18 does not attach to thepericardial tissue. Lead 18 is passed posterior when positioning thedefibrillation electrode such that the placing of the defibrillationelectrode is placed high on the heart at the base of the atrium. Thefixation helix 30 is screwed into the ventricular tissue just below theAV groove. The ring electrode is positioned adjacent the pacinglocation. Typically, pacing occurs from the ring electrode 29 to thedefibrillation coil 27 using a bipolar construction for the lead 18.

At block 210, medical personnel such as a physician determines that thetarget site has been reached with the assistance of visual images and/orresults obtained through testing. For example, the side helix 30 ispositioned over ventricular tissue near the AV groove. At block 212, theprocess of pushing the lead 18 out of catheter 100 begins by causing theinner catheter assembly 108 to gradually exit the distal end of theouter catheter 104. While the inner catheter assembly 108 begins to moveout of the distal end of the shaft of the outer catheter assembly. Inparticular, the epicardial lead 18 (e.g. 4.1 French) with a long tipelectrode used for defibrillation or in conjunction with a ringelectrode for pacing, has moved in a distal direction out of the guidingcatheter 100 toward the target location. The lead is attached to theepicardial tissue when the inner catheter assembly is extended beyondthe distal end of the outer catheter. The lead is fixated to the targetlocation by turning the lead in a clockwise direction to allow the sidehelical tip to solely screw-in to the epicardial tissue. Window 32 inside helical fixation member 30 allows the physician to visualize theturns of the side helical member 30 using the fluoroscopy during theimplantation procedure. For example, the physician can position the lead18, and, when ready, watch as the helix turns using the window portion32 as a means to track turning of the side helical fixation member 30.Without fluoroscopy, either a videoscope is used to visualize turning ofthe side helix or lead body torque feedback is employed as described inU.S. patent application Ser. No. 14/696,242, entitled METHOD ANDAPPARATUS FOR DETERMINING SUITABILITY OF A LEAD IMPLANT LOCATION,incorporated by reference in its entirety herein.

The side helical member 30, with a substantially flat and tapered distaltip and changing diameter creates a “wedging effect” of the tissue suchthat the tissue has a thicker edge at a proximal end and a thinner edgeat distal end of the tapered tip of side helical member 30. The diameterchange associated with fixation member 30 ranges from about 1.5 mm toabout 2.5 mm. Additionally, the distal tip of the side helix 30 isconfigured to perform a minimum of at least ¾ turns in epicardialtissue. The distal tip of the side helix 30 solely enters and attachesto epicardial tissue. The flat pitch of the distal tip reducesauto-rotation.

In contrast to the presently disclosed lead 18, the lead in Stokes etal. is unable to be fixated solely in the epicardial tissue since theStokes et al. lead penetrates the epicardium, and resides mid-myocardialfor stimulation. Additionally, the Stokes et al. distal tip increasesauto-rotation.

The IMD 10 is then implanted in the abdominal area while the shockvectors are positioned across the atria through the ventricles to thedevice. The ring electrode is positioned just below the AV groove at theepicardial surface. Lead 18 is placed on epicardial surface and pacesthe left ventricle at a basal location.

Once the lead 18 is placed at the desired location and the IMD 10 isimplanted, any equipment not intended for long term implant, e.g. guidecatheter, stylet, guidewire, etc. can be removed. For example, theguiding catheter and sheaths (e.g. outer sheaths are about 9 to 10French) are then slit and removed. Thereafter, the IMD is placed in anappropriate location.

By employing method 200, a catheter can be used to place the epicardiallead in any location around the surface of the heart such as atrial leaddeployment, left ventricular lead deployment, lead in the right atrium,lead fixed to the right ventricle, and lead fixed to a backside of theheart. It is beneficial to be able to use a single catheter for leadplacement anywhere around the heart and not be limited to placementlocations of the lead due to guide catheter constraints such as beingunable to get behind the heart.

Epicardial lead implantation requires surgical access to allowsufficient room to position and fixate the pacing lead tip by eithersutures or a right angle helical screw component. Surgical access ismore traumatic and requires longer recovery time as compared topercutaneous implant methods.

FIG. 14 involves a method 300 of using an implantable medical devicewith an epicardial lead 18 extending therefrom. At block 302, a cardiacsignal is sensed via a pace/sense electrode on the epicardial lead 18.At block 304, pulses are delivered to epicardial tissue using anepicardial lead 18. The epicardial lead 18 has a sharpened elongatedflat free end perpendicular to the lead body and angled toward an insideof the set of winding.

FIGS. 16A-16D through FIGS. 18A-18D depict minimally invasive subxyphoiddelivery tool (e.g. catheter 108) that has one of the distal tips400-900 employed for placement of the side helix active fixationepicardial lead 18. Delivery tool distal tips 400-900 are used to placelead 18 via a single percutaneous access site. Delivery tool distal tips400-900 gain access to the pericardial space and navigate around theheart to the desired location to place lead 18 epicardially. Eachdelivery tool distal tips 400-900 on the catheter ensures that the sidehelix active fixation mechanism 30 engages solely with epicardial tissueand not the pericardial sac, which is necessary to ensure that thetherapy is directed into the epicardial tissue.

The catheter distal tip (also referred to as a protrusion or shovel) isformed or attached at the distal end of the delivery device (alsoreferred to as a catheter and shown in FIG. 15) to slide betweenepicardial tissue and the pericardial sac. The distal tip is movable tocover the side helical fixation member 30 to ensure that the helicalfixation member 30 is directly positioned solely into the epicardialsurface and not pericardial sac. For example, when delivering the lead18 (i.e. lead 18 protrudes away or past the distal end of the catheter)the helix 30 becomes exposed so that the physician can determine thelocation of helix 30 relative to the catheter 108. Once the helix 30 isexposed, the physician can either pull the lead 18 in a proximaldirection or can push the catheter distally over the lead 18 in order toshield the helix 30 on lead 18. The distal tip, which serves as ashield, covers the helix 30 to ensure that the helix 30 will not attachto the pericardial sac and will only enter the epicardial tissue. Whenthe physician is satisfied with the lead position, the catheter with theshield shown in FIGS. 16-18, will be retracted. A slitting tool is usedto remove the catheter 108 from the lead 18.

FIGS. 16A-16D show one embodiment of a catheter tip 400. FIG. 16Adepicts a side view of catheter tip 400. FIG. 16B shows catheter tip400, rotated 90 degrees from its position in FIG. 16A, therebydisplaying a concave surface 408 with a substantially open rectangularportion formed by sides 404 and distal end 402. FIG. 16C depicts a sideview of the catheter tip 400 slightly rotated from its position in FIG.16A to show a portion of a side of the tip 400. Distal tip 400 isfurther rotated from FIG. 16C to its position in FIG. 16D to show afuller portion of a side 404 of the tip 400.

The distal tip 400 is formed at a distal end of a catheter body 406 thatincludes a lumen to receive lead 18. Surface 408 (also referred to as aroof or shield) has a small radius of curvature so that surface 408 isslightly concave and serves to cover helix 30. Extending from surface408 is substantially straight distal and side surfaces 402, 404. Distaland side surfaces 402, 404 have curved ends 410, 412 to reduceunnecessary trauma to the tissue. Optionally, the ends of each surface404, 414 and 401 are smooth to further reduce tissue trauma.

FIGS. 17A-17B are schematic diagrams depicting another embodiment of acatheter tip 500 in which a longer half-cut away open rectangularportion exists. The distal catheter tip 500 extends at a distal end of acatheter body 506. Tip 500 includes surface 508 that is configured witha small radius of curvature so that surface 508 is slightly concave atsides 504 that extend from surface 508. Surface 508 serves to coverhelix 30. Distal end 502 is formed distally of side surfaces 502, 504.Distal and side surfaces 502, 504 are substantially straight. Distal andside surfaces 502, 504 have smooth ends 510, 512 to reduce unnecessarytrauma to the tissue. Optionally, the ends of each surface 504, 514 and501 are smooth to further reduce tissue trauma.

FIGS. 17-17D are schematic diagrams depicting an embodiment of a sharplyangled cut catheter tip 600. The distal catheter tip 600 extends fromcatheter body 606. Surface 608, has a small radius of curvature so thatsurface 608 is concave and covers helix 30. Extending from surface 608are substantially curved side surfaces 604 with a distal end 602 thatform a substantially elliptical opening. Side surface 604 is sharplytapered compared to the side surface 704 of a similarly shaped tip ofFIGS. 17E-F Distal and side surfaces 602, 604 have curved ends 602, 610to reduce unnecessary trauma to the tissue.

FIGS. 17E-17F are schematic diagrams depicting another embodiment of acatheter distal tip 700. The distal catheter tip 700 extends at a distalend of catheter body 706. Tip 700 is configured with a radius ofcurvature so that surface 708 is concave, with substantially curveddistal and side surfaces 702, 704. Side surface 704 is less tapered orsharply cut than the side surface 604 of a similarly shaped tip. Distaland side surfaces 702, 704 have curved ends 710, 712 to reduceunnecessary trauma to the tissue and to shield helix 30.

FIGS. 18A-18B are schematic diagrams depicting an embodiment of acatheter tip. The distal catheter tip 800 extends from catheter body806. Surface 808 is configured with a small radius of curvature so thatsurface 808 is concave. Extending from surface 808 are substantiallycurved distal and side surfaces 802, 804 that form a substantiallyelliptical opening to cover helix 30. Distal and side surfaces 802, 804that extend to curved ends 810, 812 to reduce unnecessary trauma to thetissue.

FIGS. 18C-18D show one embodiment of a catheter tip 900. FIG. 18A is aschematic diagram depicting a side view of an embodiment of a cathetertip while FIG. 16B shows a concave surface 908 with a substantially openrectangular portion formed by sides 904 and distal end 902. FIG. 18Cdepicts a side view of the catheter tip slightly rotated from FIG. 18Ato show a portion of a side of the tip 900 while FIG. 18D is furtherrotated from FIG. 18C to show a fuller portion of a side of the tip 900.

The distal catheter tip 900 is formed at a distal end of a catheter body906 that includes a lumen to receive lead 18. Surface 908 (also referredto as a roof) has a small radius of curvature so that surface 908 isslightly concave. Extending from surface 908 is substantially straightdistal and side surfaces 902, 904. Distal and side surfaces 902, 904have curved ends 910, 912 to reduce unnecessary trauma to the tissue.Optionally, the ends or edges of each surface 904, 914 and 901 aresmooth to further reduce tissue trauma.

Distal tips 400-900 are formed by cutting away a portion of a tip orusing a mold to form the tips. Tips 400-900 comprise tungsten carbidefilled polyether blockamide (PEBAX®) but can comprise other suitablematerials. Catheter tip 400-900 can be made before, during or after acatheter manufacturing fusion process.

The epicardial lead 18, disclosed herein, can be used for delivery oftherapy including CRT, left ventricular only pacing, defibrillation,and/or any bradycardia indication. In particular, the epicardial lead 18utilizes a lumenless lead body design, distal high voltage coil to bepositioned in the superior region of the pericardial space (i.e.transverse sinus) and fixated with a side fixation helix just proximalto the high voltage coil into the epicardial surface of the posteriorLV. Either one or two ring electrodes are positioned just proximal tothe side fixation helix 30 to provide ventricular pacing and sensingwith additional atrial sensing in the integrated bipolar vector. Skilledartisans appreciate that while the delivery device(s) described hereinhave been described as delivering epicardial devices, it should beappreciated that transvenous leads can also be delivered with thedelivery devices. Additionally, distal tips 400-900 for the catheter 108can be used for a single catheter or an inner catheter to deliver avariety of leads. In addition to delivering epicardial leads,transvenous leads may also be delivered.

The following paragraphs enumerated consecutively from 1 to 24 providefor various aspects of the present disclosure. In one embodiment, amedical device comprising:

an implantable medical electrical epicardial lead that comprises:

-   -   (a) an insulative lead body that includes a proximal end and a        distal end;    -   (b) at least one conductor disposed in the lead body; and    -   (c) a side helical fixation member, disposed a distance from the        distal end, the side helical fixation member comprising a set of        windings configured to wrap around the lead body circumference,        the side helical fixation member including a distal tip        comprising a sharpened elongated flat free end that is        perpendicular to the lead body and angled toward an inside of        the set of windings.        2. The medical device of embodiment 1 wherein the fixation        member includes a tapered distal tip having a substantially flat        pitch.        3. The medical device of any of embodiments 1-2 wherein the flat        pitch of the distal tip of the fixation member is less than 45°.        4. The medical device of any of embodiments 1-3 wherein a        diameter change is associated with the tapered distal tip to        create a wedging effect on tissue that causes the distal tip to        solely remain in epicardial tissue.        5. The medical device of any of embodiments 1-4 wherein the        diameter change associated with distal tip ranges from about 1.5        mm to about 2.5 mm.        6. The medical device of any of embodiments 1-5 wherein the flat        free end is greater than 350 degrees around a circumference of        the side helical fixation member.        7. The medical device of any of embodiments 1-6 wherein a clear        polymer is introduced over the open portion of the side helical        fixation member, the clear polymer configured to allow a        physician to visualize turning of the side helical fixation        member into tissue.        8. The medical device of any of embodiments 1-7 wherein a        polymer is introduced over the open portion of the side helical        fixation member and over a portion of the set of windings to        secure the side helical fixation member to the lead body.        9. The medical device of any of embodiments 1-8 wherein the        distal tip of the side helical fixation member is configured to        perform a minimum of at least ¾ turn in tissue.        10. The medical device of any of embodiments 1-9 wherein the        side helical fixation member disposed at a distance of about 3        cm to about 12 cm from the distal end.        11. The medical device of any of embodiments 1-10 wherein the        side helical fixation mechanism has a first wind that extends a        small distance D2 to the second wind.        12. The medical device of any of embodiments 1-11 wherein a        steep angle exists into the first wind of the helical fixation        mechanism.        13. The medical device of any of embodiments 1-12 wherein a        shallow angle into tip exists in the side helical fixation        mechanism.        14. A method for employing a medical device having a housing, a        processor disposed within the housing, and a medical electrical        epicardial lead connected to the processor through a connector        module, the method comprising:    -   using the epicardial lead to sense a response from cardiac        tissue, the lead comprising:        -   (a) an insulative lead body that includes a proximal end and            a distal end;        -   (b) at least one conductor disposed in the lead body; and        -   (c) a side helical fixation member, disposed a distance from            the distal end, the side helical fixation member comprising            a set of windings configured to wrap around a lead body            circumference, the side helical fixation member including a            distal tip comprising a sharpened elongated flat free end            that is perpendicular to the lead body and angled toward an            inside of the set of windings; and    -   delivering electrical pulses through the lead to tissue of a        patient in response to sensing the response.        15. A medical device system comprising:

a delivery device having a proximal end and a distal end with aninterior therebetween, the distal end having a distal tip, an opening tothe interior of the delivery device at the distal end of the device, theopening and extending longitudinally proximal from the distal end of thedevice, the opening defined by longitudinally extending side edges and adistal edge at the distal end of the delivery device;

an implantable medical electrical epicardial lead that comprises:

(a) an insulative lead body that includes a proximal end and a distalend;

(b) at least one conductor disposed in the lead body; and

(c) a side helical fixation member, disposed a distance from the distalend, the side helical fixation member comprising a set of windingsconfigured to wrap around the lead body circumference, the side helicalfixation member including a distal tip comprising a sharpened elongatedflat free end that is perpendicular to the lead body and angled towardan inside of the set of windings,

-   -   wherein the distal tip of the delivery device is movable over        the side helical fixation member.        16. The medical device system of embodiment 15 wherein the        distal tip of the delivery device having a concave surface with        a distal edge and side edge.        17. The medical device system of any of embodiments 15-16        wherein the distal tip of the delivery device includes curved        distal edge and side edges.        18. The medical device system of any of embodiments 15-17        wherein the distal tip of the delivery device includes straight        distal edge and a side edges.        19. The medical device system of any of embodiments 15-18        wherein the distal tip of the delivery device includes straight        distal edge and a side edges are smooth.        20. The medical device system of any of embodiments 15-19        wherein the distal tip of the delivery device includes straight        distal edge and side edges without sharp edges.        21. The medical device system of any of embodiments 15-20        wherein the distal tip of the delivery device includes a        rectangular opening.        22. The medical device system of any of embodiments 15-21        wherein the distal tip of the delivery device includes an        elliptical opening.        23. A system for employing a medical device having a housing, a        processor disposed within the housing, and a medical electrical        epicardial lead connected to the processor through a connector        module, the method comprising:    -   processor means for using the epicardial lead to sense a        response from cardiac tissue, the lead comprising:        -   (a) an insulative lead body that includes a proximal end and            a distal end;        -   (b) at least one conductor disposed in the lead body; and        -   (c) a side helical fixation member, disposed a distance from            the distal end, the side helical fixation member comprising            a set of windings configured to wrap around a lead body            circumference, the side helical fixation member including a            distal tip comprising a sharpened elongated flat free end            that is perpendicular to the lead body and angled toward an            inside of the set of windings; and    -   delivering electrical pulses through the lead to tissue of a        patient in response to sensing the response.

A kit comprising:

-   -   a delivery device having a proximal end and a distal end with an        interior therebetween, the distal end having a distal tip, an        opening to the interior of the delivery device at the distal end        of the device, the opening and extending longitudinally proximal        from the distal end of the device, the opening defined by        longitudinally extending side edges and a distal edge at the        distal end of the delivery device;    -   an implantable medical electrical epicardial lead that        comprises:        -   (a) an insulative lead body that includes a proximal end and            a distal end;    -   (b) at least one conductor disposed in the lead body; and    -   (c) a side helical fixation member, disposed a distance from the        distal end, the side helical fixation member comprising a set of        windings configured to wrap around the lead body circumference,        the side helical fixation member including a distal tip        comprising a sharpened elongated flat free end that is        perpendicular to the lead body and angled toward an inside of        the set of windings,        -   wherein the distal tip of the delivery device is movable            over the side helical fixation member.

Although the present invention has been described in considerable detailwith reference to certain disclosed embodiments, the disclosedembodiments are presented for purposes of illustration and notlimitation and other embodiments of the invention are possible. It willbe appreciated that various changes, adaptations, and modifications maybe made without departing from the spirit of the invention and the scopeof the appended claims.

What is claimed is:
 1. A medical device comprising: an implantablemedical electrical epicardial lead that comprises: (a) an insulativelead body that includes a proximal end and a distal end; (b) at leastone conductor disposed in the lead body; and (c) a side helical fixationmember, disposed a distance from the distal end, the side helicalfixation member comprising a set of windings extending around acenterline and configured to wrap around the lead body circumference,the side helical fixation member including a distal tip comprising asharpened elongated free end and comprising a final one of the windingsdefining an angle of 15 degrees or less with regard to a lineperpendicular to the centerline.
 2. The medical device of claim 1wherein a diameter change is associated with the final one of thewindings to create a wedging effect on tissue that causes the distal tipto solely remain in epicardial tissue.
 3. The medical device of claim 2wherein the diameter change associated with the final one of thewindings ranges from 1.5 mm to 2.5 mm.
 4. The medical device of claim 1wherein the final one of the windings extends greater than 350 degreesaround a circumference of the side helical fixation member.
 5. Themedical device of claim 1 wherein a clear polymer is introduced over theopen portion of the side helical fixation member, the clear polymerconfigured to allow a physician to visualize turning of the side helicalfixation member into tissue.
 6. The medical device of claim 1 wherein apolymer is introduced over the open portion of the side helical fixationmember and over a portion of the set of windings to secure the sidehelical fixation member to the lead body.
 7. The medical device of claim1 wherein the distal tip of the side helical fixation member isconfigured to perform a minimum of at least ¾ turn in tissue.
 8. Themedical device of claim 1 wherein the side helical fixation memberdisposed at a distance of 3 cm to 12 cm from the distal end.
 9. Themedical device of claim 1 wherein the side helical fixation mechanismhas a first wind that extends a small distance D2 to the second wind.10. The medical device of claim 9 wherein a steep angle exists into thefirst wind of the helical fixation mechanism.
 11. The medical device ofclaim 10 wherein a shallow angle into tip exists in the side helicalfixation mechanism.
 12. A system for employing a medical device having ahousing, a processor disposed within the housing, and a medicalelectrical epicardial lead connected to the processor through aconnector module, the system comprising: processor means for using theepicardial lead to sense a response from cardiac tissue, the leadcomprising: (a) an insulative lead body that includes a proximal end anda distal end; (b) at least one conductor disposed in the lead body; and(c) a side helical fixation member, disposed a distance from the distalend, the side helical fixation member comprising a set of windingsextending around a centerline and configured to wrap around a lead bodycircumference, the side helical fixation member including a distal tipcomprising a sharpened free end and comprising a final one of thewindings defining an angle of 15 degrees or less with regard to a lineperpendicular to the centerline; and the system further comprising meansfor delivering electrical pulses through the lead to tissue of a patientin response to sensing the response.